While the prevalence of dental caries has declined for the majority of U.S. children in recent decades, there are profound disparities in dental caries experience where young children from low-income or minority families suffer a disproportionate share of the disease burden. To effectively address the problem of caries in the primary dentition of high-risk children, preventive efforts should be directed at these children beginning at a very early age. The WIC supplemental nutritional program is one of the very few programs that serves children at very young ages, and it also serves children from low-income families. However, there are limited data available about the oral health of WIC-enrolled populations, and studies have not longitudinally followed subjects in such a population. Thus, the goals for the proposed study are to longitudinally track caries experience in WIC-enrolled children; to assess methods to enhance subject recruitment and retention in these populations and to gather longitudinal caries risk data on WIC populations. We will also explore how S. mutans clonal types change over time, as well as how they interact with host genetic markers and predict caries development in these high-risk young children. Specifically, the study will follow a cohort of WIC-enrolled 1-year-old children for 18 months in Muscatine and Louisa counties in Iowa - two rural counties with large Hispanic populations. Collection of pilot data in this population will allow our research team and others to continue research aimed at reducing oral health disparities, including longitudinal trials of preventive interventions. Moreover, interventions centered at WIC programs have the potential to become sustainable caries-prevention programs for high-risk children throughout the country. We will collect data on caries occurrence, beverage consumption, fluoride exposures, S. mutans levels and clonal type, and host genetic markers, and we will assess different methods of recruiting and retaining subjects in this high-risk population. Data from this pilot study will be of great value and will position the study team to effectively conduct future intervention studies to reduce oral health disparities.